Cytotoxicity and Mitochondrial Dysregulation Caused by α-Synuclein in Dictyostelium discoideum

Fernando, Sanjanie; Allan, Claire Y.; Mroczek, Katelyn; Pearce, Xavier; Sanislav, Oana; Fisher, Paul R.; Annesley, Sarah J.

doi:10.3390/cells9102289

Cited by 10 publications

(34 citation statements)

References 89 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In otherwise unstressed cells, we found that DJ-1 knockdown caused an elevation of mitochondrial respiration [18] (Figure 1). Similar mitochondrial hyperactivity was recently reported in Dictyostelium cells overexpressing the wild type or PD-associated mutant forms of α-synuclein [58], in cultured human neuroblastoma cells treated with exogeneous α-synuclein [59], in lymphoblasts from idiopathic PD patients [28] and in fibroblasts from genetic PD patients with Parkin mutations [29]. This raises the intriguing possibility that mitochondrial hyperactivity is an initiating event in these different types of PD.…”

supporting

confidence: 80%

The Parkinson’s Disease-Associated Protein DJ-1 Protects Dictyostelium Cells from AMPK-Dependent Outcomes of Oxidative Stress

Chen

Annesley

Jasim

et al. 2021

Cells

Self Cite

View full text Add to dashboard Cite

Mitochondrial dysfunction has been implicated in the pathology of Parkinson’s disease (PD). In Dictyostelium discoideum, strains with mitochondrial dysfunction present consistent, AMPK-dependent phenotypes. This provides an opportunity to investigate if the loss of function of specific PD-associated genes produces cellular pathology by causing mitochondrial dysfunction with AMPK-mediated consequences. DJ-1 is a PD-associated, cytosolic protein with a conserved oxidizable cysteine residue that is important for the protein’s ability to protect cells from the pathological consequences of oxidative stress. Dictyostelium DJ-1 (encoded by the gene deeJ) is located in the cytosol from where it indirectly inhibits mitochondrial respiration and also exerts a positive, nonmitochondrial role in endocytosis (particularly phagocytosis). Its loss in unstressed cells impairs endocytosis and causes correspondingly slower growth, while also stimulating mitochondrial respiration. We report here that oxidative stress in Dictyostelium cells inhibits mitochondrial respiration and impairs phagocytosis in an AMPK-dependent manner. This adds to the separate impairment of phagocytosis caused by DJ-1 knockdown. Oxidative stress also combines with DJ-1 loss in an AMPK-dependent manner to impair or exacerbate defects in phototaxis, morphogenesis and growth. It thereby phenocopies mitochondrial dysfunction. These results support a model in which the oxidized but not the reduced form of DJ-1 inhibits AMPK in the cytosol, thereby protecting cells from the adverse consequences of oxidative stress, mitochondrial dysfunction and the resulting AMPK hyperactivity.

show abstract

supporting

confidence: 80%

The Parkinson’s Disease-Associated Protein DJ-1 Protects Dictyostelium Cells from AMPK-Dependent Outcomes of Oxidative Stress

Chen

Annesley

Jasim

et al. 2021

Cells

Self Cite

View full text Add to dashboard Cite

show abstract

“…Another of the phenotypes in which coexpression of tau and α-synuclein had opposing effects was in mitochondrial respiratory function. Previously we showed that α-synuclein did not cause an impairment in mitochondrial function but instead it increased respiratory activity coordinately in all components measured (Fernando et al, 2020). This result was consistent with increases in mitochondrial respiration seen in lymphoblast cell lines made from iPD patients (Annesley et al, 2016), fibroblasts from iPD patients (Haylett et al, 2016) and when neuroblastoma cells were seeded with α-synuclein fibrils (Ugalde et al, 2020).…”

Section: Discussionsupporting

confidence: 85%

“…Tau was detected using an anti-tau antibody coupled with Alexa-Fluor 594-conjugated secondary antibody and was seen throughout the cytoplasm of the cell. α-synuclein had previously been seen to localise to the cortex of the cell in D. discoideum (Fernando et al, 2020). To detect α-synuclein and tau in the cotranformants anti-tau and anti-α-synuclein antibodies were coupled with Alexa-Fluor 594 and 488-conjugated secondary antibodies respectively.…”

Section: Tau Is Localised Throughout the Cytoplasm In D Discoideum Whereas α-Synuclein Is Localised To The Cortexmentioning

confidence: 99%

“…Error bars represent standard errors (D) Thermotaxis. AX2, tau strain, α-synuclein [HPF885-data taken from previous experiments (Fernando et al, 2020)], and cotransformants were measured for accuracy of thermotaxis (κ), normalised and plotted against temperature. Temperature is expressed in arbitrary units (1-8) corresponding to agar surface temperatures of 14-28 • C. α-synuclein caused no thermotaxis defect in comparison to the WT.…”

Section: Coexpression Of Tau and α-Synuclein Positively Affects Growth On Plates But Negatively Affects Axenic Growthmentioning

confidence: 99%

See 1 more Smart Citation

Interactions and Cytotoxicity of Human Neurodegeneration- Associated Proteins Tau and α-Synuclein in the Simple Model Dictyostelium discoideum

Mroczek

Fernando

Fisher

et al. 2021

Front. Cell Dev. Biol.

Self Cite

View full text Add to dashboard Cite

The abnormal accumulation of the tau protein into aggregates is a hallmark in neurodegenerative diseases collectively known as tauopathies. In normal conditions, tau binds off and on microtubules aiding in their assembly and stability dependent on the phosphorylation state of the protein. In disease-affected neurons, hyperphosphorylation leads to the accumulation of the tau protein into aggregates, mainly neurofibrillary tangles (NFT) which have been seen to colocalise with other protein aggregates in neurodegeneration. One such protein is α-synuclein, the main constituent of Lewy bodies (LB), a hallmark of Parkinson’s disease (PD). In many neurodegenerative diseases, including PD, the colocalisation of tau and α-synuclein has been observed, suggesting possible interactions between the two proteins. To explore the cytotoxicity and interactions between these two proteins, we expressed full length human tau and α-synuclein in Dictyostelium discoideum alone, and in combination. We show that tau is phosphorylated in D. discoideum and colocalises closely (within 40 nm) with tubulin throughout the cytoplasm of the cell as well as with α-synuclein at the cortex. Expressing wild type α-synuclein alone caused inhibited growth on bacterial lawns, phagocytosis and intracellular Legionella proliferation rates, but activated mitochondrial respiration and non-mitochondrial oxygen consumption. The expression of tau alone impaired multicellular morphogenesis, axenic growth and phototaxis, while enhancing intracellular Legionella proliferation. Direct respirometric assays showed that tau impairs mitochondrial ATP synthesis and increased the “proton leak,” while having no impact on respiratory complex I or II function. In most cases depending on the phenotype, the coexpression of tau and α-synuclein exacerbated (phototaxis, fruiting body morphology), or reversed (phagocytosis, growth on plates, mitochondrial respiratory function, Legionella proliferation) the defects caused by either tau or α-synuclein expressed individually. Proteomics data revealed distinct patterns of dysregulation in strains ectopically expressing tau or α-synuclein or both, but down regulation of expression of cytoskeletal proteins was apparent in all three groups and most evident in the strain expressing both proteins. These results indicate that tau and α-synuclein exhibit different but overlapping patterns of intracellular localisation, that they individually exert distinct but overlapping patterns of cytotoxic effects and that they interact, probably physically in the cell cortex as well as directly or indirectly in affecting some phenotypes. The results show the efficacy of using D. discoideum as a model to study the interaction of proteins involved in neurodegeneration.

show abstract

“…The elevated respiration was accompanied by an elevated ATP steady state and elevated ROS production [ 72 ]. Since that publication, the findings have been confirmed in LCLs from a larger cohort of idiopathic PD patients (unpublished data) and in other cellular PD models, including exposure of the neuroblastoma cell line SH–SY5Y to fibrillar alpha–synuclein [ 73 ] and in the simple eukaryotic model Dictyostelium discoideum , expressing genetically manipulated PD-associated genes, including α-synuclein [ 74 ] and DJ-1 [ 75 ]. In all cases, mitochondrial respiration was increased, not decreased.…”

Section: Parkinson’s Disease (Pd)mentioning

confidence: 93%

Lymphoblastoid Cell Lines as Models to Study Mitochondrial Function in Neurological Disorders

Annesley

Fisher

2021

IJMS

Self Cite

View full text Add to dashboard Cite

Neurological disorders, including neurodegenerative diseases, are collectively a major cause of death and disability worldwide. Whilst the underlying disease mechanisms remain elusive, altered mitochondrial function has been clearly implicated and is a key area of study in these disorders. Studying mitochondrial function in these disorders is difficult due to the inaccessibility of brain tissue, which is the key tissue affected in these diseases. To overcome this issue, numerous cell models have been used, each providing unique benefits and limitations. Here, we focussed on the use of lymphoblastoid cell lines (LCLs) to study mitochondrial function in neurological disorders. LCLs have long been used as tools for genomic analyses, but here we described their use in functional studies specifically in regard to mitochondrial function. These models have enabled characterisation of the underlying mitochondrial defect, identification of altered signalling pathways and proteins, differences in mitochondrial function between subsets of particular disorders and identification of biomarkers of the disease. The examples provided here suggest that these cells will be useful for development of diagnostic tests (which in most cases do not exist), identification of drug targets and testing of pharmacological agents, and are a worthwhile model for studying mitochondrial function in neurological disorders.

show abstract

Cytotoxicity and Mitochondrial Dysregulation Caused by α-Synuclein in Dictyostelium discoideum

Cited by 10 publications

References 89 publications

The Parkinson’s Disease-Associated Protein DJ-1 Protects Dictyostelium Cells from AMPK-Dependent Outcomes of Oxidative Stress

The Parkinson’s Disease-Associated Protein DJ-1 Protects Dictyostelium Cells from AMPK-Dependent Outcomes of Oxidative Stress

Interactions and Cytotoxicity of Human Neurodegeneration- Associated Proteins Tau and α-Synuclein in the Simple Model Dictyostelium discoideum

Lymphoblastoid Cell Lines as Models to Study Mitochondrial Function in Neurological Disorders

Contact Info

Product

Resources

About